Add Developer Hints to CONTRIBUTING.md, Issue #625

Added some developer hints per Issue #625.

CONTRIBUTING.md

@@ -1,42 +1,90 @@
 # Contributing to RomWBW
 
-> **WARNING**: The `dev` branch of RomWBW has been deprecated as of v3.4.  All Pull Requests should now target the `master` branch.
+> **WARNING**: The `dev` branch of RomWBW has been deprecated as of
+  v3.4.  All Pull Requests should now target the `master` branch.
 
-Contributions of all kinds to RomWBW are welcomed and greatly appreciated.
+Contributions of all kinds to RomWBW are welcomed and greatly
+appreciated.
 
 - Reporting bug(s) and suggesting new feature(s)
 - Discussing the current state of the code
-- Submitting a fixes and enhancements
+- Submitting fixes and enhancements
 
 ## RomWBW GitHub Repository
 
-The [RomWBW GitHub Repository](https://github.com/wwarthen/RomWBW) is the primary location for developing, supporting, and distributing RomWBW.  Although input is gladly accepted from almost any channel, the GitHub Repository is preferred.
+The [RomWBW GitHub Repository](https://github.com/wwarthen/RomWBW) is
+the primary location for developing, supporting, and distributing
+RomWBW.  Although input is gladly accepted from almost any channel, the
+GitHub Repository is preferred.
 
-- Use **Issues** to report bugs, request enhancements, or ask usage questions.
+- Use **Issues** to report bugs, request enhancements, or ask usage
+  questions.
 - Use **Discussions** to interact with others
 - Use **Pull Requests** to submit content (code, documentation, etc.)
 
 ## Submitting Content
 
-This RomWBW Project uses the standard [GitHub Flow](https://docs.github.com/en/get-started/quickstart/github-flow).  Submission of content changes (including code) are ideally done via Pull Requests.
+This RomWBW Project uses the standard [GitHub Flow]
+(https://docs.github.com/en/get-started/quickstart/github-flow).
+Submission of content changes (including code) are ideally done via Pull
+Requests.
 
-- Submitters are advised to contact [Wayne Warthen](mailto:wwarthen@gmail.com) or start a GitHub Discussion prior to starting any significant work.  This is simply to ensure that submissions are consistent
-  with the overall goals and intentions of RomWBW.
-- All submissions should be based on the `master` branch.  To create your submission, fork the RomWBW repository and create your branch from `master`.  Make (and test) your changes in your personal fork.
-- Please update relevant documentation and the `ChangeLog` found in the `Doc` folder.
-- You are encouraged to comment your submissions to ensure your work is properly attributed.
-- When ready, submit a Pull Request to merge your forked branch into the RomWBW master branch.
+- Submitters are advised to contact [Wayne Warthen](mailto:wwarthen@
+  gmail.com) or start a GitHub Discussion prior to starting any
+  significant work.  This is simply to ensure that submissions are
+  consistent   with the overall goals and intentions of RomWBW.
+- All submissions should be based on the `master` branch.  To create
+  your submission, fork the RomWBW repository and create your branch from
+  `master`.  Make (and test) your changes in your personal fork.
+- Please update relevant documentation and the `ChangeLog` found in the
+  `Doc` folder.
+- You are encouraged to comment your submissions to ensure your work is
+  properly attributed.
+- When ready, submit a Pull Request to merge your forked branch into the
+  RomWBW master branch.
 
 ## Coding Style
 
-Due to the nature of the project, you will find a variety of coding styles.  When making changes to existing code, please try to be consistent with the existing coding style.  You may not like the current style, but no one likes mixed styles
-in one file/module.
+Due to the nature of the project, you will find a variety of coding
+styles.  When making changes to existing code, please try to be
+consistent with the existing coding style.  You may not like the current
+style, but no one likes mixed styles in one file/module.
 
-Be careful with white space.  RomWBW is primarily assembly langauge code.  The use of tab stops at every 8 characters is pretty standard for assembler.  If you use something else, then your code will look odd when viewed by others.
+Be careful with white space.  RomWBW is primarily assembly langauge
+code.  The use of tab stops at every 8 characters is pretty standard for
+assembler.  If you use something else, then your code will look odd
+when viewed by others.
 
-In most cases, the use of `<cr><lf>` line endings is preferred.  This is standard for the operating systems of the era that RomWBW provides.  Also note that CP/M text files should end with a ctrl-Z (0x1A).  This is not magically added by the
-tools that generate the disk images.
+In most cases, the use of `<cr><lf>` line endings is preferred.  This is
+standard for the operating systems of the era that RomWBW provides.
+Also note that CP/M text files should end with a ctrl-Z (0x1A).  This is
+not magically added by the tools that generate the disk images.
+
+## Hints for Developers
+
+- The majority of RomWBW is assembled with TASM (and it's compatible
+  equivalent sz80as).  These tools have quirks that are very subtle.  For
+  example, TASM does not evaluate expressions in the standard way.  It
+  uses a left to right approach.  Check the TASM documentation carefully.
+
+- The following two Z80 instructions highlight a common issue with the
+  Z80 assembler syntax.  Parens in operands frequently indicate an
+  indirect reference.  To treat the operand as an expression, use the
+  second format.
+
+```
+	LD	A,(5+5)		; Load A with the value at address 10
+	LD	A,0+(5+5)	; Load A with the value 10
+```
+
+- The RomWBW documewntation in the Doc directory is generated with a
+  process outside of the normal build process.  To update documentation,
+  please update the .md files in Source/Doc.  Those are the Markdown
+  source files for the documentation.  The PDF files will be updated
+  offline from those.
 
 ## License
 
-RomWBW is licensed under GPLv3.  When you submit code changes, your submissions are understood to be under the same [GPLv3 License](https://www.gnu.org/licenses/gpl-3.0.html) that covers the project.
+RomWBW is licensed under GPLv3.  When you submit code changes, your
+submissions are understood to be under the same [GPLv3 License]
+(https://www.gnu.org/licenses/gpl-3.0.html) that covers the project.